FIELD OF THE INVENTION
The invention relates to a fuel tank for a motor vehicle with a collector tank for extracting air from the fuel tank. The collector tank is connected to the interior of the fuel tank and to a pressure-equalizing device, in particular an activated carbon filter.
Such fuel tanks are often used in motor vehicles and are known from practice. The fuel tank usually has a total of two collector tanks for extracting air from it during refueling and during operation of the motor vehicle. The connection of the interior of the fuel tank and of the collector tank takes place via lines. By the collector tanks, the liquid fuel flowing in via the lines is separated from gaseous constituents and air. This prevents liquid fuel from passing into the pressure-equalizing device and damaging, in particular, the activated carbon filter.
The disadvantage with the known fuel tank is that, as a result of the large number of lines, it involves a high outlay to install and it has pronounced levels of fuel emission.
It is accordingly an object of the invention to provide a fuel tank which overcomes the above-mentioned disadvantages of the prior art devices of this general type, which results in particularly low levels of fuel emission and is as straightforward as possible to install.
With the foregoing and other objects in view there is provided, in accordance with the invention, a fuel tank for a motor vehicle. The fuel tank contains a fuel tank body having walls defining an interior, a pressure-equalizing device, a pump having a suction side, and a collector tank for extracting air from the fuel tank body. The collector tank is connected to the interior of the fuel tank body and to the pressure-equalizing device. More specifically, the collector tank is disposed within the fuel tank body and is connected to the suction side of the pump.
The problem is solved according to the invention in that the collector tank is disposed within the fuel tank or forms a subregion of the wall thereof.
By virtue of the configuration, the fuel tank according to the invention does not require any line between its interior and the collector tank since the collector tank is directly adjacent to the interior of the fuel tank and can thus simply be connected thereto. This results in the installation of the fuel tank according to the invention being simplified to a pronounced extent. Furthermore, the omission of the line having to be laid makes it possible to avoid the two connections of the line to the collector tank and the fuel tank. Since there are particularly high levels of fuel emission through the connections, the configuration of the fuel tank according to the invention results in the levels of fuel emission being vastly reduced. A further advantage of the configuration is that, in the event of the motor vehicle crashing, the risk of lines and tanks being wrenched away from the fuel tank is kept particularly low.
When the motor vehicle is cornering or is in an inclined position, it is possible for fuel to pass, via the collector tank, into the pressure-equalizing device and then into the surroundings. According to an advantageous development of the invention, however, fuel can be reliably retained within the fuel tank if a line leading to the pressure-equalizing device can be shut off by a changeover valve. Furthermore, the configuration prevents the activated carbon filter located in the pressure-equalizing device from being wetted with fuel and permanently damaged as a result.
It would be possible for the fuel tank according to the invention, like the known fuel tank, to have a collector tank in each case for extracting air during operation and for extracting air during refueling. The fuel tank according to the invention, however, is of particularly straightforward construction if the changeover valve is configured for alternating connection of the pressure-equalizing device to the collector tank or to the interior of the fuel tank. As a result, it is additionally possible for the fuel tank to be produced particularly cost-effectively.
Constant wetting of the changeover valve with fuel can easily be avoided, according to another advantageous development of the invention, if the changeover valve is disposed on the inside of the top wall of the fuel tank. This helps to reduce fuel emissions further.
It would be possible for the changeover valve to be actuated, for example, mechanically by a closure cover of a filler inlet of the fuel tank or a changeover flap that can be moved in the filler inlet by a fuel nozzle. However, according to another advantageous development of the invention, the changeover valve can be activated at any time, in dependence on traveling situations of the motor vehicle, if the changeover valve is a solenoid valve.
It helps to simply the installation of the fuel tank according to the invention further if the line leading to the pressure-equalizing device is routed through an installation cover of a fuel-delivery unit.
In particular in the case of fuel tanks with flat geometries, fuel can pass into the collector tank. With increasing internal pressure within the fuel tank, the fuel could be forced to the pressure-equalizing device. The situation where the fuel is led into the pressure-equalizing device can be reliably avoided, according to another advantageous development of the invention, if the collector tank is connected to the suction side of a pump. This makes it possible for fuel present in the collector tank to be extracted by suction.
It would be possible for the pump to be driven, for example, directly by an electrical device. According to another advantageous development, however, air and fuel can equally be delivered if the pump is a suction jet pump.
According to another advantageous development of the invention, the collector tank can easily separate liquid fuel from gaseous fuel and air if the collector tank has a funnel-shaped depression. In order to allow the liquid fuel to run off, the depression may have an opening.
Foaming and swirling of fuel present in the collector tank can easily be avoided, according to another advantageous development of the invention, if the pump is connected to the depression of the collector tank.
The pump may be disposed at any desired location in the fuel tank. The fuel tank according to the invention, however, requires a particularly low level of outlay as far as laying lines is concerned if the pump is disposed within the collector tank.
It would be possible for the suction jet pump to be supplied with fuel as the working fluid, for example, by a dedicated electrically operated pump. According to another advantageous development of the invention, however, the consumption of electrical energy for the pump can easily be avoided if, the pump, which is configured as a suction jet pump, is connected to a flow line or return line of an internal combustion engine. For this purpose, the suction jet pump may be connected to a flow line or a return line of the internal combustion engine of the motor vehicle.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a fuel tank, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.